Research will be undertaken to employ ion and gas sensing membrane electrodes for clinical analysis of substrates, enzymes, immunoagents, electrolytes, and other body fluid constituents. Methods will be developed for the determination of clinically important substances in serum, while blood, and urine involving the employment of crystal membrane, enzyme or antigen coated, and other electrodes both in the individual sample mode and in high speed automated flow systems. It is expected that the proposed approach will result in desirable simplifications of the chemistries involved, by elimination of dialysis and color development steps, and will produce a significant reduction in analysis costs, through the simplification of expensive optical and electronic instrumentation as well as a reduction in the quantities and number of required reagents.